Electrical relays



Sept. 3, 1957 N. c. SHAW 2,805,301

ELECTRICAL RELAYS Filed July 24, 1953 2 Sheets-Sheet 2 mmvrox. Noble 6! Shaw ukp zwt H15 ATTORNEY F129? BY United States Patent ce ELECTRIAL RELAYS Noble C. Shaw, Penn Township, Allegheny County, Pa.,

assignor to Westinghouse Air Brake (Iontpany, Wilmerding, Pa., a corporation of Iennsylvania Application July 24, 1953, Serial No. 370,096

9 Claims. (Cl. 200-184) My invention relates to electrical relays, and particularly to means for eliminating the rebound or bounce of the relay contacts.

In electrical circuits wherein relays are used to initiate and control definite functions, the contacts controlled by the relays upon closing must not bounce it proper circuit control is to be achieved. It has been found that the contacts of electrical relays have a tendency to rebound or bounce upon engagement, thereby causing erratic operation and arcing across the contacts. This tendency of the relay contacts to rebound is due for th most part to the kinetic energy stored in the armature assembly of the relay during its movement from its one extreme position to its other extreme position. it has also been found that contact rebound is due in part to the resiliency of the contact fingers.

it is therefore an object of my present invention to provide an armature assembly for a relay with energy absorbing means whereby the armature assembly is brought to rest against its back stops without rebound.

Another object of my invention is to provide a relay contact operating structure whereby the energy stored in the movable spring contact fingers is transferred to the stationary contacts of the relay in such a manner that rebound of the contacts due to the resiliency of the contacts is eliminated.

in the copending application of Branko Lazich, Serial No. 221,773, filed on April 19, 1951, now Patent No. 2,775,666, dated December 25, 1956, for Electrical Relays and assigned to the common assignee hereof, there is disclosed a small, compact miniature relay having outer dimensions of approximately 1% inches in diameter and 1% inches in length, and providing six back and six front contacts. The relay therein disclosed is characterized by an armature rotatable about a vertical axis and forming the support for a cont-act actuating spider. The afore said relay is provided with six spring contact fingers secured to the closure disk sealing the enclosure in which the relay elements are mounted, the outer ends of the fingers being engaged by individual slots provided in the contact actuating spider. Back and front contacts are also secured to the closure disk and are adapted to be engaged by the spring contact fingers upon rotation of the relay armature and its attendant contact actuating spider.

Such a relay finds application in many different types of circuits, particularly in those applications in which the lightweight feature of the relay serves a major purpose, as for example, in airborne instrument and control systems. In controlling the rebound or bounce of the contacts in this type of relay, the provisions made by me neither add to the dimensions of the relay nor add to the weight of the relay.

in carrying out my invention, I provide spring contact fingers for a relay of the character indicated, which cooperate with the contact actuating spider carried by the relay armature. split ends, each of the end portions of the fingers being The contact fingers are formed with 2,805,3lli Patented Sept. 3, 1957 contacts of the relay are engaged before the relay armature engages its front stop. The slight additional travel of the armature to its front stop, after the front contacts engage, flexes the longer end portions of the spring contact fingers engaging the notches of the contact actuating spider so that the front contacts are closed with considerable pressure.

When the relay winding is deenergized, the bias of the spring contact fingers moves the contact actuating spider and its supporting armature toward the armature back stops with considerable velocity. The back stops of the relay are so spaced that the back contacts are engaged before the armature engages its back stops. The spring force of the contact fingers is thus transferred to the back contacts, the armature and spider assembly traveling an additional limited distance before the armature back stops are engaged. The spring force returning the spider is transferred from the spider to the back contacts as rapidly as possible, i. e., in an absolute minimum of armature rotation from the instant the contacts first engage to the instant the full spring force is applied to the contacts. If the increment of armature movement during the transfer of spring pressure is kept small and the entire spring force transferred during this increment of movement, the initial bounce of the contacts will be eliminated.

I further provide the armature and spider assembly with an inertia element for eliminating the secondary rebound of the contacts due to the inertia of the moving parts. The inertia element in the particular embodiment herein disclosed takes the form of a ring which is made of resilient material. The inertia ring is frictionally held within a peripheral groove provided in the contact actuating spider. The frictional force between the ring and its supporting spider is such that the ring will accelerate with the spider. This frictional force is overcome, however, When the armature assembly is suddenly deceleratcd as the armature stops are engaged to permit limited rotation of the inertia ring relative to the contact actuating spider. The forces of inertia which would tend to go into the rebound of the armature and spider assembly are thus dissipated by the friction developed between the relatively moving elements.

Other objects and characteristic features of my invention will become apparent as the description proceeds.

I shall describe one form of an armature and contact assembly embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings:

Fig. 1 is an elevational view of a relay embodying my invention, a portion of the shell being broken away and parts of the armature assembly being shown in vertical section.

Fig. 2 is a sectional view taken approximately along the line 11-11 of Fig. 1.

v Fig. 3 is an isometric view of the contact structure and armature assembly embodying my invention, while Fig. 4 is an isometric view showing the details of contact structure, a small portion of the spring contact finger being broken away for illustrating the parts to better advantage.

Referring now in detail to the drawings, the reference character 1 designates in general, a relay of the miniature type as illustrated and described in the aforesaid copending application of Branko Lazich. The relay 1 comprises a cylindrical housing or shell 2 of magnetic material. with a header or closure disk 3 seam-welded to the open end of the shell, the closure disk being provided with a plurality of glass bead inserts 4 forming the entrant means and support for a plurality of contact supporting posts 5 and two small-bore tubes 6' (only one illustrated) providing an entrant means for the operating winding connections as described in the aforesaid 'copending application.

Secured within the lower end of the shell 2 in a suitable manner is a core 7 of magnetic material. Surrounding the magnetic core of the relay is an operating. winding 8 wound on a spool 9, the ends-8a and 8b 'of the winding being brought out through the top of'the spool and led out through the small-bore tubes 6 of the closure disk. A plateor disk 10 is secured'to the top of the spool 9; openings 11' being 'providedin the plate for the winding leads 8a and 8b. The plate lll'is further provided with two upturned'sectors formin'g 'the back stops-12 for the relay armature. Secured to the plate in asuitable manner are four pole pieces 13, the pole faces 13a thereof being in planes slightly off center radially with respect to the vertical axis of the 'relay.. The pole faces 13:: form the front stopsofth'e relay armature, as Will'hereinafterappear, the pole pieces 13 being .plated with'a suitable nonmagnetic metal, such. as copper, to prevent sticking.

Recessed inthe upper end of'th'e magnetic core 7 of the relay is a bearing bushing 14 for supporting an armature assembly designated'generally by the reference character 15. The armature assembly 15 comprises an armature 16 of magnetic-material and a contact actuating member orspider 17 made of a suitable insulating material; The armature assembly 15 is secured to a vertical shaft 18, the lower end of which is journaled in the bearing bushing 14 and the upper end is journaledin a bearing bushing 19pr'ess fitted in a cup 20 secured to the closure disk 3.

The armature 16' comprises a central hub 21 having four extending arms 22 equidistantly spaced on the hub. The planes of the'armature arms are oifsetwith respect to the vertical axis of the hub so. that as the armature arms are rotated'toward the pole pieces 13, the surfaces of the armature arms and'the planes of the pole faces- 13a are substantially parallel. The underside of the armature hub 21 is counterbore'd, ,as at 23, to receive the upper end of the magnetic core 7 with some clearance. The armature hub 21 is rigidly secured to thevertical shaft 18.

Secured to the top of'the armature 16 is the spider 17, essentially cup-shaped and having a hub portion 24-fitting over the armature hub 21 and an upturned lip 25. The bottom wall 26 of the spider is formed with two arcuate slots 27 to accommodate the operating winding.

leads 8a and 8b, while the lip of the spider is notched at various points 28 around the periphery to engage the spring contact fingers as will hereinafter be described. The spider 17 is also formed with a peripheral groove 29 in the outer surface. of the lip 25. Disposed within the peripheral groove of the spider is an inertia ring 30,- the ring being made of a resilient material such as phosphor bronze or the'like. The ring is set or pretensioned to provide for the frictional engagement of the ring with the bottom of the spider groove, as will'hereinafter be more fully described.

Secured to the lower ends of the contact supporting posts 5' of the closure disk 3 are a plurality ofbackcontacts 31, front contacts 32 and spring contact fingers33. The spring contact fingers 33 (Fig. 4) are essentially U- shaped having a divergent, extending end 34; 'Two slits 33a in the heelportion of each finger provides a loop for securing the finger to a post. The extending end 34 of the finger is divided into an upper tip 35 and a lower end 36, the upper tip being the longer andextends; through The relay 1 is of the sealed type and is provided" 4 a notch 28 in the spider lip 25. The upper tip of the finger is provided with a contact 37 adapted to engage a back contact 31, while the lower end is provided with a contact 38 adapted to engage a front contact 32. It will be noted that the back and front contacts 31 and 32 are formed with surfaces arcuate in one plane, while the contacts 37 and 38 are formed with surfaces arcuate in a plane at right angles to that of the back and front contact surfaces. The arcuate surfaces provided for the contacts will compensate for any slight misalignment of the contacts, or the longitudinal flexing of the spring con tact fingers.

The spring fingers are set or pretensioned so that the back contacts 3137 are closed when the relay is deenergized, the spring finger tips engaging the sides of the notches 28 to move the spider to its one extreme position. It will be appreciated, as the description proceeds, that the upper end or tip 35 of the spring contact fingers and the lower end 36 may be set or stressed relative to each other to provide make-before-break' contacts for the relay 1.

Upon energization of the operating winding 8 of the. relay 1, the armature assembly will be rotated in a clockwise direction (Fig. 2). The edges of the spider notches will engage the spring finger tips to move the spring fingers against their bias to open the back contacts 31 37 and close the front contacts 3238. The rotation of the spider 17 is such that the front contacts 32 -38 are closed before the spider reaches its extreme position, with the result that the spring fingers 33 are under considerable tension, the front contacts being'closed with considerable pressure.

Upon deenergization of the relay operating winding, the tensioned spring fingers 33 tend to rotate the spider toward its initial extreme position with considerable velocity. While there may be a slight loss in the tension of the spring fingers as they rotate the spider counterclockwise to its initial extreme position, the increased tension of the spring is transferred to the back contacts 3137 before the spider reaches its extreme position and before the armature arms 22 engage the back stops 12. In Fig. 2 of the drawings I have illustrated the return movement of the armature assembly, the back contacts being closed while the armature arms 22 are spaced from the back stops 12. The transfer of the spring finger tension from the spider to the back contacts is made instantaneously to eliminate the initial rebound or bounce of the contacts. The back and front contacts are substantially rigid and any bounce of the contacts would be due in greater part to the resiliency of the spring fingers. By limiting the time of transfer of the trappedspring-force to the shortest possible angular displacement of the armature from the instant the contacts first engage to the instant when the entire spring force is transferred to the back contacts, I have been able to eliminate theinitial rebound of the relay contacts.

With the transfer of the spring finger tension to the back contacts, the armature assembly continues to rotate due to the inertia built up during its acceleration by the tensioned spring fingers. To dissipate the inertia stored inrthe moving armature assembly, the inertia ring 30 is provided on the contact actuating spider. The ring frictionally engages the bottom of the spider groove, the frictional force being such that the inertia ring will accelerate with the spider. The friction provided between the two elements, however, is insuffic-ient to-prevent limited continued relative rotation of the inertia ring with respect to the spider when the armature assembly is brought to a sudden stop. When the armature arms 22 of the assembly engage the back stops 12, the force of inertia built up during the return movement will overcome the'frictional force holding the inertia ring in the spidergroove. There is then a relative rotationof the inertia ring with respect to the stationary spider, the force ofinertia being dissipated in the friction developed between the inertia ring and the spider. Thus the armature assembly is held stationary against the back stops, the rebound of the armature assembly being eliminated by the action of the inertia ring, thereby eliminating the rebound or bounce of the relay contacts due to the forces of inertia.

It will thus be seen that I have provided a relay in which the contact rebound or bounce due to the resiliency of the contacts and the inertia of the armature assembly has been eliminated. The provision of abutting contact surfaces arcuate in planes at right angles for the relay contacts as herein described insures the proper engagement of the contacts despite any misalignment of the contacts or possible longitudinal flexing of the spring contact fingers. The operation of such a relay in any electrical circuit either to initiate or to control any given function is both positive and fast. With the contacts closing firmly under tension and remaining closed, a relay embodying the principles of my invention provides stable operation with no arcing between the contacts due to contact rebound.

Although I have herein shown and described only one form of a relay armature and contact assembly embodying my invention, it is to be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. An electrical relay comprising an operating winding, an armature movable between two extreme positions, biased spring fingers moving said armature to one extreme position, fixed front and back contacts adapted to be engaged respectively by the spring fingers upon movement of said armature in response to the energization and deenergization of the operating winding, means for eliminating the rebound of the contacts due to the resiliency of the contacts including a contact actuating member engaged by said spring fingers and movable with said armature, said contact actuating member maintaining said spring fingers under tension and permitting the instantaneous transfer of the spring force of said fingers to the fixed contacts during an increment of the distance the member and armature are moved, and means for eliminating the rebound of the contacts due to the inertia of the moving armature and contact actuating member including a frictionally held inertia element movable with the armature and contact actuating member and adapted to move relatively to said armature and contact actuating member to dissipate the energy stored in the moving armature and contact actuating member when said armature is stopped suddenly in its extreme position.

2. A contact actuating assembly comprising a movable member, means for limiting the movement of said member to two extreme positions, means for moving said member to its first extreme position, a spring contact finger cooperating with said movable member and biased to move said member toward its second extreme position, and front and back contacts adapted to be engaged by said spring contact finger; said spring contact finger being provided with two end portions, one longer than the other, the longer end portion engaging said armature assembly; and a contact for each end portion of the spring contact finger adapted to engage respectively with front and back contacts, the movement of the member to its first extreme position increasing the bias of said spring contact finger, the contact finger engaging the front contact before the member is moved to its first extreme position; said member being moved to its second extreme position by said spring contact finger upon release of said rotating means, the bias of the spring contact finger being transferred to the back contact during the return movement of the member by the spring contact finger before the member returns to its second extreme position.

3. A contact actuating assembly comprising a rotatable member, means for limiting the rotation of said member to two extreme positions, means for rotating said member to its first extreme position, a spring contact finger cooperating with said rotatable member and biased to rotate said member toward its second extreme position, front and back contacts adapted to be engaged by said spring contact finger; the rotation of the member to its first extreme position increasing the bias of said spring contact finger, the contact finger engaging the front contact before the member is moved to its first extreme position; the member being rotated toward its second extreme position with considerable velocity by the spring contact finger upon release of said rotating means, the bias of the spring contact finger being transferred instantaneously to the back contact before the member is moved to its second extreme position, and an inertia element rotatable with and relative to said member for frictionally absorbing the energy stored in the rotating member when said member stops in its extreme position.

4. In an electrical relay, the combination comprising, an operating winding, a rotatable armature assembly, a back stop and a front stop for limiting the rotation of said armature to two extreme positions, back and front contacts for said relay, spring contact fingers cooperating with said armature assembly and biased to rotate said armature assembly toward said back stop, said armature assembly being rotated toward said front stop upon energization of the operating winding thereby increasing the bias of said spring contact fingers, said spring contact fingers engaging the front contacts; said armature assembly being rotated toward its extreme position determined by the back stop by the bias of said spring contact fingers with considerable elocity upon deenergization of the operating winding, the bias of the spring contact fingers being transferred instantaneously to the back contacts during an increment of the distance the armature assembly moves toward its extreme position determined by the back stop, and an inertia ring frictionally engaging the armature assembly and rotatable therewith, the energy stored in the rotating armature assembly being dissipated in the friction developed between the inertia ring and the armature assembly when said ring rotates relative to said assembly upon engagement of said assembly with its stop.

5. In an electrical relay the combination comprising, an operating winding, a rotatable armature assembly, a back stop and a front stop for limiting the rotation of said armature to two extreme positions, back and front contacts for said relay, spring contact fingers cooperating with said armature assembly and biased to move said armature assembly toward said back stop, said armature assembly being rotated toward said front stop upon energization of the operating winding thereby increasing the bias of said spring contact fingers, said spring contact fingers engaging the front contacts before the armature assembly is in the extreme position determined by the front stop, said armature assembly being rotated with considerable velocity toward its extreme position determined by the back stop by the bias of said spring contact fingers upon deenergization of the operating winding, the bias of the spring contact fingers being transferred instantaneously to the back contacts before the armature assembly is in its extreme position determined by the back stop, an inertia ring frictionally engaging the armature assembly and rotatable therewith, the energy stored in the rotating armature assembly being dissipated in the friction developed between the inertia ring and the armature assembly when said ring rotates relative to said assembly upon engagement of said assembly with its stop.

6. In an electrical relay, the combination comprising, an operating winding, a rotatable armature assembly, back and front stops for limiting the rotation of said armature, front and back contacts, a spring contact finger cooperating with the armature assembly for biasing saidassernbly toward its. back stop, said: spring contact fingenbeing provided with two. end portions, one longer thanthe other,.the longer endportion engaging said armature assembly; and a contactxforv each end portion of the spring, contact finger adapted to'engage respectively with the front and back contacts; .saidannature assembly being rotated to engage its front stop. uponenergization of, the operatingwinding thereby increasing the bias. of said spring contact finger, the shorter end portion contact of said. finger engaging. thesfront contact before the armatureassembly engagesits frontstop, the longer end portion beinng flexed whenthe armature assembly engages its front stop to apply pressure to the closedfront contacts; said. armature assembly beingrotated tOWfiId'ziES back stop with considerablevelocity by the biased spring contact finger upon deenergization ofthe operating winding, the, bias of thevspring, contact. finger being transferred, instantaneously to the. back contact by engagement of the longer endportion contact on said finger with-the back contact during anincrement of the return movement of the armature assembly.

7. In an. electrical relay, the. combination comprising, an;operating gwinding, :arotatable. armature assembly, back and front stops for limiting the rotation of said armature, front and back contacts, a spring contact finger cooperating with the armature assembly for biasing said assembly towardits back stop, said springcontact finger being provided with two endportions, one longer than theother, the longer end portionengaging said armature assembly, a contact for each end portion of the spring contact finger adapted to engage respectively with the front and back, contacts, said armature assembly being rotated to engage its front stop upon energization of the operating winding thereby increasing the bias of said spring contact finger, the shorter end portion contact of said finger engaging the front contact before the armature assembly engages its front stop, the longer end portion being flexed when the armature assembly engages its front stop to apply pressure to the closed frontcontacts, said armature assembly being rotated with considerable velocity toward its back stop by the biased spring contact finger upon deenergization of the operating winding, the bias of the spring contact finger being transferred instantaneously to the back contact by'engagement of the longer end portion contact on said finger with the back contact during an increment of the return movement of the armature assembly, and an inertiaring frictionally engagingsaid armaturev assembly,

and rotatable; therewith, the energy storedin the rotating.

armature assembly being, dissipated inthe friction developed between -said ring and armatureassembly when said ring, rotates relativeto said assembly upon engage-. ment of the armature assembly with its stop.

8. In an electrical relay, the combination comprising, a contact finger of resilient material bent to a substantially. U-shapedform, means for securing one end of said finger, :the other end of said finger being divided longi-.

tudinally to form two .end portions of different lengths,

contact making elements on each of said end portions, and.

contact actuating means engagingthe longer end portion of said contact finger.

9. In an electrical relay, the combination comprising, a contact finger of resilient material'bentto a substantially.

U-shaped form, means for securing one end of said fin ger, the other end of said finger extending beyond the secured end and divergent therefrom, the extended divergent end of the finger being divided longitudinally to form two end portions of different lengths, contact makingielements on each of said end portions, and contact actuating mean engaging the longer end portion of the contact finger.

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